This invention relates to a conveyor. More particularly, this invention relates to a helical conveyor especially useful for the conveyance of projectiles.
A conveyor for transporting projectiles is disclosed in U.S. Pat. No. 4,236,441, invented by John Turner et al., patented Dec. 2, 1980, assigned to the assignee of the present invention, and hereby incorporated by reference.
Although the prior art includes numerous constructions for conveyors, prior art conveyors have generally been subject to one or more of several significant disadvantages. In particular, such conveyors are often limited to a single starting point and a single ending point. For example, a conventional conveyor belt will receive articles to be conveyed at one end and convey the articles to another end. Changing the starting point or the ending point of the conveyor belt usually requires major redesign.
Although some conveyors are sufficiently adaptable to readily allow change in the starting point of conveyance and the ending point, such conveyors are generally ill suited towards the rapid conveyance of a large number of articles from one point to another point. For example, a conventional crane as often used in construction projects allows the conveyance of articles between any two points within the range of the crane. However, the crane must repeatedly traverse the distance between the starting point of conveyance and the ending point of conveyance. This step requires operator control and is time consuming.
Yet another disadvantage common to the prior art is that conveyors are often rigid in configuration. That is, even those conveyors which are not absolutely fixed to a particular starting point and ending point, may still require that the starting point and the ending point be a particular distance apart. In addition to requiring a particular distance between the starting point and the ending point, prior art conveyors are often limited to a particular geometrical configuration between the starting point and the ending point. That is, the conveyor is usually fixed in a straight line or a particular predetermined curve. In either case, the conveyor is greatly limited in operation because of this.
Prior art conveyors are further disadvantageous in that they often do not adequately secure the conveyed article to the conveyor itself. A jolting or other disturbance may therefore cause the conveyed articles to fall off the conveyor as, for example, a conventional conveyor belt. At the other extreme, those prior art conveyors which require the conveyed articles to be positively attached to the conveyor itself may slow down the conveyance operation by requiring time consuming attaching and unattaching steps. For example, a conventional crane often attaches to the eyelet of a load or article to be conveyed. The article must be attached to the crane at the starting point and unattached from the crane at the ending point.
Prior art conveyors often require large driving structures which greatly hinder the portability and/or adaptability of the conveyor for various uses. That is, even in the case of a conveyor which is somewhat portable, the use of a large and cumbersome driving structure may make it cumbersome to move the conveyor.